Opioid drugs act by binding to specific receptors in neurons in the brain and other parts of the body. Opioid receptors are normally responsible for many different processes in the body. These receptors can regulate the body’s response to stress and pain, breathing, temperature regulation, mood, motivation, and digestive activity.
Table 1. Classes of Opioids
|Types of Opioids|
|Naturally Occurring Opiates||Opium, Morphine, Codeine, Heroin|
|Opiate Derivatives||Vicodin (Hydrocodone), Percocet (Oxycodone), Oxycontin (Long-acting Oxycodone)|
|Synthetic (Man-made) Opioids||Methadone, Duragesic Patch (Fentanyl)|
(2007). Opiates binding to opiate receptors in the nucleus accumbens: increased dopamine release. Retrieved from: National Institute on Drug Abuse
Different types of opioid drugs can act as agonists (receptor activators) or antagonists (receptor blockers). For example, heroin is a strong opioid-receptor agonist. By activating opioid receptors, heroin can cause feelings of euphoria and relaxation while also causing slowed breathing, decreased gastrointestinal movement, and many other opioid effects.
 Kreek, M. J. (2008). Neurobiology of Opioiates and Opioids. In M Galanter & H Kleber (Ed.), Textbook of Substance Abuse and Treatment (4th ed.) Arlington, VA: American Psychiatric Publishing.